[JRTJH]

The Dawn will likely cut a "bunch of crud" out of your tank. It doesn't take a "whole bottle", but half a cup or so of the original blue Dawn should clean your tank well. Plan on rinsing it 3 or 4 times after the "Dawn treatment". The "blue tank deodorant" isn't really a "permanent type" deodorizer. It only lasts a few days and may be losing its "perfume" before you get back the following week.

A couple of other things that could be happening: Make sure you have water that stays in the toilet bowl. The water acts as a "seal" and prevents gas from bubbling past the O-ring seal. Also, if you're leaving your gray tank valves open, you could have campground sewer gas being pushed into your rig, through the gray tanks and up into your sink traps. Keep your gray tank valves closed if you're not in the RV. Another possibility is the gray tanks themselves. Food particles have a way of "ripening" in the gray tank and can easily smell just as bad as the black tank. You might want to do the "Dawn treatment" on your gray tanks also, especially if you don't see good results with the black tank cleaning.